¹ Boscovich, R. J., Theoria Philosophiae Naturalis (Vienna, 1758)Google Scholar. The Venetian edition of 1763 was translated by Child, J. M.: A Theory of Natural Philosophy (London, 1922)Google Scholar. References will be to this Latin-English edition.

² See [Stewart, Balfour and Tait, P. G.,] The Unseen Universe; or Physical Speculations on a Future State (3rd edn., London, 1875), 102Google Scholar; Poynting, J. H., “The Growth of the Modern Doctrine of Energy” [1884], Collected Scientific Papers (Cambridge, 1920), 569 f.Google Scholar, and “Atomic Theory (Medieval and Modern)” [1909], Ibid., 729. See also Stallo, J. B., The Concepts and Theories of Modern Physics (Cambridge, Mass., 1960), 179 ff.CrossRefGoogle Scholar (republication of the 3rd, 1888 edn.).

³ For example, see Meyerson, Emile, Identity and Reality (trans.) Loewenberg, Kate (London, 1930), 79Google Scholar; Whittaker, E. T, A History of the Theories of Aether and Electricity (2 vols., London, 1951–1953), i, 193Google Scholar; Jammer, Max, Concepts of Force, a Study in the Foundations of Dynamics (Harper edn., New York, 1962), 184.Google Scholar

⁴ Faraday, Michael, Experimental Researches in Electricity (3 vols., London, 1839–1855), ii, 284–293.Google Scholar I will refer to this work as Electricity, followed by a volume number, and, where appropriate, Faraday's paragraph number, as in the following example: Electricity, ii, par. 2146. Otherwise page numbers will be given, for example: Electricity, ii, 284Google Scholar. Faraday's Diary, Being the Various Philosophical Notes of Experimental Investigation made by Michael Faraday, D.C.L., F.R.S. during the Years 1820–1862 (London, 1932–1936)Google Scholar contains little material relevant to this paper which is not in the Electricity.

⁵ Pearce Williams, L., Michael Faraday (London, 1965).Google Scholar

⁶ See Spencer, J. Brookes, “Boscovich's Theory and its Relation to Faraday's Researches: An Analytic Approach”, Arch. Hist. Exact Sci., iv (1967), 184–202.CrossRefGoogle Scholar

⁷ Williams, , op. cit. (5), 78.Google Scholar Williams nowhere provides evidence for this assumption. See Spencer, Brookes, op. cit. (6).Google Scholar

⁸ Ibid., 306 ff. Thus, Williams States that “Faraday's use of the theory of point atoms was here so basic that the presentation of his own ideas suffered seriously from his failure to make his debt to this theory explicit” (Ibid., 309).

⁹ For a full discussion of this tradition, see Heimann, P. M. and McGuire, J. E., “Newtonian Forces and Lockean Powers: Concepts of Matter in Eighteenth-Century Thought”, Historical Studies in the Physical Sciences, iii (1971).Google Scholar

¹⁰ Faraday, , Electricity, ii, 290.Google Scholar

¹¹ Boscovich's ideas were much more widely known in early nineteenth-century Britain than Williams indicates, in fact, accounts of Boscovich's Theoria can be found, for example, in Robison, John, A System of Mechanical Philosophy (4 vols., Edinburgh, 1822), i, 267–368Google Scholar; and in the article “Boscovich”, Encyclopaedia Britannica, Supplement to the Third Edition (Edinburgh, 1803), i, 96–110.Google Scholar See also Olson, Richard, “The Reception of Boscovich's Ideas in Scotland”, Isis, lx (1969), 91–103.CrossRefGoogle Scholar

¹² See Graves, R. P., Life of Sir William Rowan Hamilton (3 vols., Dublin and London, 1882–1889) ii, 95Google Scholar, and also Ibid., i, 593.

¹³ Williams seems to argue that in Faraday's later thought the supposed “Boscovicheanism” of the “Speculation” was abandoned, for if lines of forces were “the key to the unity of force phenomena” (Williams, , op. cit. (5), 435)Google Scholar, then Boscovich's theory of point atoms would cease to be necessary, for Williams states that in his later thought Faraday “had two types of polarity to work with; one was associated with the particles of matter and followed directly from the theory of point atoms … The other involved the lines of force” (Ibid., 391). In this paper it is emphasized that the theory of the primacy of lines of force followed from the ideas in the “Speculation”, for the significant feature of the “Speculation” was the notion of “matter” as “forces” diffused through space, as distinct from a Boscovichean theory of point atoms.

For a different interpretation of Faraday from that of Williams, one more in agreement with that advanced in the present paper, see Hesse, Mary B., Forces and Fields: The Concept of Action at a Distance in the History of Physics (London, 1961), 199–201.Google Scholar

¹⁴ For an account of the relation between Faraday and Maxwell, see Heimann, P. M., “Maxwell and the Modes of Consistent Representation”, Arch. Hist. Exact Sci., vi (1970), 171–213.CrossRefGoogle Scholar

¹⁵ For a convincing reconstruction of Faraday's discovery, in which Boscovicheanism is not assigned a role, see Williams, , op. cit. (5), 169–183, 191–202.Google Scholar

¹⁶ Electricity, i, par. 60.Google Scholar

¹⁷ Ibid., par. 61.

¹⁸ Ibid., par. 60.

¹⁹ Ibid., par. 71.

²⁰ Ibid., par. 73.

²¹ Ibid.

²² Ibid., par. 870. Faraday explicitly refers to Berzelius here.

²³ Ibid., par. 869.

²⁴ Ibid., par. 852.

²⁵ This same caution can be seen in Faraday's reference to Boscovich in the 1844 “Speculation”, as having supposed the atomic theory which involved the fewest assumptions (Electricity, ii, 289 f.)Google Scholar. His only other citation of Boscovich, in the 1846 “Thoughts on Ray-vibrations”, was for an even more limited purpose (Electricity, iii, 448).Google Scholar

²⁶ Electricity, i, par. 949.Google Scholar

²⁷ Ibid., par. 1304.

²⁸ Ibid., par. 218–219.

²⁹ Ibid., par. 220.

³⁰ Ibid., par. 231, 238.

³¹ Ibid., par. 242.

³² Electricity, iii, par. 3269.Google Scholar

³³ Electricity, i, par. 1304.Google Scholar

³⁴ Ibid., par. 1231.

³⁵ Ibid., par. 1224.

³⁶ Ibid., par. 1295.

³⁷ Ibid., par. 1298.

³⁸ Ibid., par. 1298, 1671.

³⁹ Ibid., par. 1661, 1729, 1733.

⁴⁰ Ibid., par. 1729.

⁴¹ Ibid., par. 1338.

⁴² Ibid., par. 1669, 1670.

⁴³ Ibid., par. 1675.

⁴⁴ Ibid., par. 1231.

⁴⁵ His concept of particulate polarization was expressed clearly enough for Maxwell to find it satisfactory in the Treatise on Electricity and Magnetism (Oxford, 1873)Google Scholar, where he remarked that Faraday's induction “is a polarized state of the particles of the dielectric, each particle being positive on one side and negative on the other” (§ 54). The evidence does not support Williams' contention, with respect to this theory of polarization, that Faraday did not suppose a separation of charge, but that Faraday supposed the particles were “distorted”, and that “this distortion seems to be what Faraday meant by polarization … There was not, in short, a separation of the forces so that equal quantities of positive and negative force were concentrated at each end of the particle” (Williams, , op. cit. (5), 307).Google Scholar

⁴⁶ Electricity, i, par. 1665n; see also par. 1615, 1164n.Google Scholar

⁴⁷ Ibid., par. 1164n.

⁴⁸ Ibid., par. 1616.

⁴⁹ Ibid., par. 1165.

⁵⁰ Hare, R., “A Letter to Prof. Faraday, on certain Theoretical Opinions”, Phil. Mag., xvii (1840), 44Google Scholar; Electricity, ii, 251.Google Scholar Though at this time, as he later conceded, Hare appears to have been somewhat confused by the meaning Faraday attached to “contiguity” (see Hare, R., “Second Letter to Prof. Faraday”, Phil. Mag., xvii (1841), 465–477)Google Scholar, this did not affect the validity of this point here, for Hare was questioning Faraday's denial of action at “sensible distances” at the same time as supposing action at “the distance of half an inch”.

⁵¹ Electricity, ii, 252.Google Scholar

⁵² Ibid., 267.

⁵³ Ibid., 284.

⁵⁴ Ibid., 286f.

⁵⁵ Electricity, iii, par. 2787.Google Scholar

⁵⁶ Electricity, ii, 289.Google Scholar

⁵⁷ Ibid., 290.

⁵⁸ Ibid.

⁵⁹ Ibid., 291.

⁶⁰ This manuscript, which is at the Institution of Electrical Engineers, London, and dated 19 February 1844, has been published: see Levere, T. H., “Faraday, Matter, and Natural Theology—Reflections on an Unpublished Manuscript”, Brit.J. Hist. Sci., iv (1968–1969), 96–107.Google Scholar

⁶¹ In my view this remark of Faraday's does not justify the inference Levere draws from it, that Faraday adhered to “force atomism” because “it fitted in with the world picture imposed by his religion” (Levere, , op. cit. (60), 101)Google Scholar. Faraday clearly had a religious approach to nature, but his remark in the “Matter” MS. indicates his belief in God's omnipotence over the order of nature, not that his religious views determined his adoption of any particular theory of matter, or that “force atomism” more readily displayed the action of divine power over nature. The theological implications of Faraday's theory of matter warrants further examination.

⁶² Boscovich, , Theory of Natural Philosophy (London, 1922), § 7.Google Scholar

⁶³ Faraday erroneously connected the notion of separating the matter from the atoms with Boscovich, for he remarked that “in Boscovich's theory a [the particles of matter away from the powers] disappears” (Electricity, ii, 290).Google Scholar If as I shall suggest, Faraday derived these arguments from Priestley, he could well have gained the impression that this was Boscovich's view from Priestley. Priestley identified Boscovich's ideas with those of John Micheli, and in expounding these ideas stated that “take away attraction and repulsion and matter vanishes” (Disquisitions Relating to Matter and Spirit (2nd edn., 2 vols., Birmingham, 1782), i, 36).Google Scholar

⁶⁴ Boscovich, , op. cit. (62), § 8.Google Scholar

⁶⁵ Ibid., § 516. As Maxwell pointed out, speaking of atoms as “centres of force without attributing to them any finite extension … would be quite legitimate, provided centre of force is admitted to have mass” (draft MS. of “A Dynamical Theory of the Electromagnetic Field”, University Library, Cambridge, Add. MSS. 7655). Maxwell noted that Boscovich “did not forget, however, to endow his mathematical points with inertia” (Maxwell, J. C., “Action at a Distance”, Scientific Papers, ed. Niven, W. D. (2 vols., Cambridge, 1890), ii, 317)Google Scholar. Whewell, William remarked that a “collection of mere centers of force can have no inertia” (Philosophy of the Inductive Sciences, 2nd edn., 2 vols., London, 1847), i, 433nGoogle Scholar, using this as an argument against Boscovich. I am grateful to Dr D. M. Knight for drawing my attention to this note, which does not appear in the first edition.

⁶⁶ Electricity, ii, 291.Google Scholar

⁶⁷ Ibid., 292 f.

⁶⁸ Ibid., 293.

⁶⁹ Ibid.

⁷⁰ Boscovich, , op. cit. (62), § 360.Google Scholar

⁷¹ Electricity, iii, 447–452.Google Scholar

⁷² Ibid., 449.

⁷³ A similar argument was used by Kant in the Metaphysische Anfangsgründe der Naturwissenschaft (Riga, 1786).Google Scholar Thus, Kant argued that “Matter fills space, not by its mere existence, but by a special moving force”, Kant's Prolegomena and Metaphysical foundations of Natural Science, trans. Bax, E. B. (London, 1883), 170Google Scholar, the only forces of matter which could be conceived being the attractive and repulsive forces (Ibid., 171).

⁷⁴ See also Hutton, James, An Investigation of the Principles of Knowledge, and of the Progress of Reason, from Sense to Science and Philosophy (3 vols., Edinburgh, 1794), ii 383 ff.Google Scholar, for a discussion of the “powers” of matter. A full analysis of the significance of the term “power”—which was derived from Locke—in Hutton and Priestley will be given in Heimann, P. M. and McGuire, J. E., op. cit. (9).Google Scholar Faraday's idea that matter consisted of its powers was later followed by Croll, James, “On the Nature of Heat Vibrations”, Phil. Mag., xxvii (1864), 346 f.CrossRefGoogle Scholar; “On Certain Hypothetical Elements in the Theory of Gravitation”, Ibid., xxxiv (1867), 449–460.

⁷⁵ Newton, Isaac, Opticks (4th edn., Dover reprint, London, 1952), 395.Google Scholar

⁷⁶ See Desaguliers, J. T., A Course of Experimental Philosophy (3rd edn., 2 vols., London, 1763), ii, 337Google Scholar; Smith, Robert, A Compleat System of Opticks (London, 1738), 88 fGoogle Scholar.; Rowning, John, A Compendious System of Natural Philosophy (4th edn., London, 1745), part 2, 6.Google Scholar

⁷⁷ Robison, John, op. cit. (11), i, 253 ff.Google Scholar

⁷⁸ Young, Thomas, A Course of Lectures on Natural Philosophy and the Mechanical Arts (2 vols., London, 1807), i, 618.Google Scholar

⁷⁹ Taylor, R. (ed.), Scientific Memoirs, i (London, 1837), 448–469.Google Scholar

⁸⁰ Williams, , op. cit. (5), 295.Google Scholar

⁸¹ Phil. Mag., x (1837), 317.Google Scholar

⁸² Electricity, ii, 293.Google Scholar

⁸³ Electricity, iii, 450.Google Scholar

⁸⁴ Mossotti, , op. cit. (79), 448.Google Scholar

⁸⁵ Gravitation was explained, because as “the repulsion of the molecules of matter is a little less than their attraction of the atoms of the aether, or than the mutual repulsion of the atoms themselves, this will be sufficient to leave an excess of attraction which … would exactly represent the universal attraction” (Ibid., 450). It was this which interested Faraday, for, as he told Whewell, it agreed with “my notion which I think I mentioned to you that Universal Gravitation is a mere residual phenomenon of Electrical Attraction and Repulsion” (Williams, , op. cit. (5), 295).Google Scholar Faraday made attempts to demonstrate this by experiment, though forced, in 1850, to conclude his first attempt with the words: “Here end my trials for the present. The results are negative. They do not shake my strong feeling of the existence of a relation between gravity and electricity, though they give no proof that such a relation exists” (Electricity, iii, par. 2717).Google Scholar

⁸⁶ Phil. Mag., x (1837), 320 f.Google Scholar

⁸⁷ Exley, Thomas, “Remarks on Mr. Mossotti's Theory of Physics”Google Scholar, Ibid., 496–504.

⁸⁸ Ibid., 497.

⁸⁹ In this they differed from theorists who identified the forces of attraction and repulsion with two kinds of matter. See Knight, Gowin, An Attempt to Demonstrate, that all the Phaenomena in Nature, May te explained by Two Simple Active Principles, Attraction and Repulsion (London, 1748)Google Scholar; Higgins, Bryan, A Philosophical Essay Concerning Light (London, 1776)Google Scholar; Hutton, James, Dissertations on Different Subjects in Natural Philosophy (Edinburgh, 1792)Google Scholar and A Dissertation upon the Philosophy of Light, Heat, and Fire (Edinburgh, 1794)Google Scholar; Harrington, Robert, A New System on Fire and Planetary Life (London, 1796)Google Scholar; Walker, Adam, A System of Familiar Philosophy (new edn., 2 vols., London, 1802).Google Scholar See Heimann, and McGuire, , op. cit. (9).Google Scholar

⁹⁰ Report of the British Association for the Aduanccment of Science, 1836 (London, 1837)Google Scholar, “Notes and Abstracts of Communications”, 30; Report of the British Association … 1838 (London, 1839)Google Scholar, “Notes and Abstracts of Communications”, 68.

⁹¹ Phil. Mag., x (1837), 357.Google Scholar This note by the editors followed a short paper advancing a theory somewhat similar to those of Mossotti and Exley: Cooper, Paul, “Notice of a Theory of Molecular Action”Google Scholar, Ibid., 355–357.

⁹² Exley, Thomas, Principles of Natural Philosophy: or, a New Theory of Physics, founded on Gravitation and applied in explaining the general properties of matter, the phaenomena of Chemistry, Electricity, Galvanism, Magnetism, and Electro-Magnetism (London, 1829), 3.Google Scholar

⁹³ Ibid., xx.

⁹⁴ Ibid., xxi.

⁹⁵ Ibid., 470.

⁹⁶ Ibid., 473.

⁹⁷ Ibid., xxvii.

⁹⁸ Priestley, Joseph, Disquisitions Relating to Matter and Spirit (2nd edn., 2 vols., Birmingham, 1783), i, 22.Google Scholar

⁹⁹ McGuire, J. E., “Body and Void and Newton's De Mandi Systemate: some new sources”, Arch. Hist. Exact Sci., iii (1966), 206–248.CrossRefGoogle Scholar See also Thackray, Arnold, “‘Matter in a Nut-shell’: Newton's Opticks and Eighteenth-century Chemistry”, Ambix, xv (1968), 29–53.CrossRefGoogle Scholar The notion of the paucity of matter in the universe in eighteenth-century natural philosophy will be discussed further in the paper referred to in note (9). Examples of such statements include: Walker, Adam, A System of Familiar Philosophy (new edn., 2 vols., London, 1802), i, 38Google Scholar, where Priestley's language was followed: “the whole matter of the universe is supposed capable of being compressed into the size of a walnut”.

¹⁰⁰ Boscovich did not replace “matter” by its forces (see above (63–65)). It should be noted that Priestley's account of Michell's ideas is our only source for knowledge of his theory of matter. Priestley emphasized that Michell's theory explained the penetrability of bodies to light (Priestley, , op. cit. (98), i, 24).Google Scholar See also Higgins, Bryan, A Philosophical Essay Concerning Light (London, 1776), 246.Google Scholar It was this requirement of the extreme porosity of matter—to explain the penetrability of bodies to light—that Thomas Young opposed in arguing against the particulate theory of light, for the wave theory of light “does not require the disproportion [between matter and void] to be by any means so great” (op. cit. (78), i, 459).Google Scholar

¹⁰¹ Priestley, , op. cit. (98), i, 27.Google Scholar

¹⁰² Ibid., ii.

¹⁰³ Ibid., 11.

¹⁰⁴ Ibid., 36.

¹⁰⁵ Ibid., 26.

¹⁰⁶ Ibid., 13.

¹⁰⁷ Ibid., 25.

¹⁰⁸ See Exley's reply to his critics in his Physical Optics; or the Phaenomena of Optics explained according to Mechanical Science; and on the known principles of gravitation (London, 1834), 204 f.Google Scholar

¹⁰⁹ Vincent, B., A New Classified Catalogue of the Library of the Royal Institution (London, 1857), 198.Google Scholar See Priestley, Joseph, The History and Present State of Discoveries relating to Vision, Light, and Colours (London, 1772), 390–394.Google Scholar This passage was quoted in the Disquisitions, i, 24–28.Google Scholar

¹¹⁰ See Vincent, , op. cit. (109), 191, 228.Google Scholar

¹¹¹ Hutton, Charles, A Mathematical and Philosophical Dictionary (London, 1795–1796), ii, 83.Google Scholar

¹¹² Young, , op. cit. (78), i, 607.Google Scholar

¹¹³ Ibid., i, 458.

¹¹⁴ Ibid., ii, 323.

¹¹⁵ The first edition (1782) was in the library (see Vincent, , op. cit. (109), 190)Google Scholar, as was the first volume of the fourth edition (which will be quoted here).

¹¹⁶ Nicholson, William, An Introduction to Natural Philosophy (4 edn., 2 vols., London, 1796), i. 7.Google Scholar

¹¹⁷ Ibid., 15.

¹¹⁸ Priestley made it clear (op. cit. (98), i, 26)Google Scholar that he denied the (Newtonian) notion of passive, inert matter found in Baxter, Andrew, An Enquiry into the Nature of the Human Soul (London, 1733).Google Scholar Baxter emphasized that “passivity, and want of power in a substance” was “necessary in the universe” (Ibid., 28), for by denying activity as inherent in matter he was able to maintain the “necessity of an immaterial Mover in all spontaneous motions” (Ibid., 36), that is, a distinction between matter and spirit. By denying the notion of passive, solid matter, Priestley was able to deny the matter-spirit duality. For a discussion of Newton's theory of active principles see McGuire, J. E., “Force, Active Principles, and Newton's Invisible Realm”, Ambix, xv (1968), 154–208.CrossRefGoogle Scholar

¹¹⁹ In the absence of knowledge of Faraday's theological views, little more can be said on this question. See (61). His membership of the Sandemanian Church is clearly relevant.

¹²⁰ Electricity, iii, 447.Google Scholar

¹²¹ Ibid., 451.

¹²² Williams, , op. cit. (5), 381.Google Scholar

¹²³ Electricity, iii, par. 2479.Google Scholar

¹²⁴ Ibid., par. 2472.

¹²⁵ Ibid., par. 2429.

¹²⁶ Ibid., par. 2640–2701.

¹²⁷ Wilhelm Weber argued that there was a difference between the molecules of paramagnetic and diamagnetic substances, and his theory was based on Ampère's theory that a magnet consisted of molecules within each of which electric currents circulated. Weber suggested that the molecules of diamagnetic substances did not have any electric currents circulating within them, but such currents were induced by a magnet. He assumed that “in the single molecules, or around them, closed paths exist in which the … [electrical] fluids can move without resistance” (Weber, , “On the Connexion of Diamagnetism with Magnetism and Electricity”, Tyndall, and Francis, (eds.), Scientific Memoirs, Natural Philosophy (London, 1853), 166).Google Scholar Thus, according to Weber, currents circulated within the molecules of paramagnetic bodies, but not within the molecules of diamagnetic bodies, and he argued that paramagnetic and diamagnetic bodies would exhibit opposite polarities, under the same conditions of excitation, as the currents in the magnetic molecules circulated in the opposite direction to the induced currents in diamagnetic molecules. See Weber, W., “On the Excitation and Action of Diamagnetism according to the Laws of Induced Currents”, Taylor, Scientific Memoirs, v (London, 1852), 477–488Google Scholar (Werke, Wilhelm Webers (6 vols., Berlin 1892–1894) iii 255–268).Google Scholar

¹²⁸ Electricity, iii, par. 2806–2835.Google Scholar

¹²⁹ Ibid., par. 3243–3299.

¹³⁰ Ibid., par. 3258.

¹³¹ Ibid., par. 3361.

¹³² Ibid., par. 3307.

¹³³ Ibid., par. 3249.

¹³⁴ For the necessity of a “magnetic medium”, see Electricity, iii, par. 3277, 3361.Google Scholar Though Faraday did consider the possibility that the lines of forces were transmitted by an action which was “a function of the aether” (Ibid., par. 3075), he was sceptical as to the existence of the aether (Ibid., 451).

¹³⁵ Faraday endeavoured to explain gravitation by supposing lines of gravitational force spread out through space (Electricity, iii, 574).Google Scholar Maxwell echoed this hope in a letter to Faraday of 9 November 1857. This letter is at the Institution of Electrical Engineers, London, and was published in Campbell, L. and Garnett, W., Life of James Clerk Maxwell (2nd edn., London, 1884), 202–204.Google Scholar For a discussion of this, see my paper cited in (14).

¹³⁶ Electricity, iii, 572Google Scholar, and “On the Conservation of Force”, Experimental Researches in Chemistry and Physics (London, 1859), 443–463.Google Scholar

¹³⁷ Electricity, iii, par. 2787.Google Scholar

¹³⁸ Ibid., par. 2789.

¹³⁹ Priestley, Joseph, The History and Present State of Electricity (3rd edn., 2 vols., London, 1775)) i xiv.Google Scholar Cf. Faraday in the “Speculation”: “Light and electricity are two great and searching investigators of the molecular structure of bodies” (Electricity, ii, 286).Google Scholar